Statistical Issues in The
Design, Analysis, and Interpretation of Environmental Epidemiologic
Studies

Suhartono

ABSTRACT

A primary objective of many
environmental epidemiologic studies is to associate potentially adverse
exposures received in the community (or workplace) with potential biologic
effects. Such association are strengthened considerably if
exposure-response relationshipcan be found.Identification and
characterization of exposure-response relationship in the residential
community setting are made difficult by the general absence of documented
data on individuals at risk and their potential exposures.

There are some limitations of
epidemiological studies of communities exposed to environmental
contaminants i.e. populations living in the vicinity of point source of
exposure are usually small; persons living in any given area are usually
heterogeneous either with respect to characteristics that can influence
many health outcomes independently of exposure; actual population
exposures are generally poorly defined and for many chemicals little or
nothing known about toxicological effects; many of the health endpoints of
interest are either rare; publicity related to the episode under study may
produce or accentuate reporting bias; and the conduct of community studies
is made difficult by the presence of a highly charged atmosphere of anger
and fear.

There are some statistical aspects
of community based investigations of health effects are i.e. exploratory
vs. confirmatory study; determining sample size and statistical power;
identifying and controlling systematic sources of error; assessing
interaction; determining the level of the investigation; power with
ecological studies; limitations of multivariate models, etc.